1. Field of the Invention
The present invention relates generally to a natural language dialogue system. More particularly, the invention relates to a system for conversation with a speaker displayed on a display screen of a computer, such as an anthropomorphic character by a natural language input, which can be via voice or keyboard.
2. Description of the Related Art
In the conventional technology of a speech conversation using a anthropomorphic character, such as that disclosed in Japanese Unexamined Patent Publication No. Heisei 5-216618, it is a primary system to provide the anthropomophic character in a system for establishing conversation between the system and a user one-on-one. In conversation through such conventional system, conversation is progressed by alternate speech of the system and user.
On the other hand, in Japanese Unexamined Patent Publication No. Heisei 10-31497, Japanese Unexamined Patent Publication No. Heisei 10-20884 and Japanese Unexamined Patent Publication No. Heisei 8-166797, there have been proposed systems providing speech guidance relating to candidates of next speech from the system to the user in order to make conversation between the system and the user smooth.
In the foregoing prior art, the user is inherently required to respond to the speech of the system. Therefore, when the user cannot react (respond) to proposal and inquiry from the system, conversation is inherently stopped. On the contrary, in the system where guidance messages are constantly spoken by the system side, speech of the system inherently becomes long for the guidance messages to degrade smoothness of progress of conversation. On the other hand, concerning application to perform information retrieval through speech conversation, since speech of the user is frequently required in the system, in which response of the user to the inquire of the system is inherent, load on the user becomes significant. Moreover, it should be difficult to list items for selection and select the item only by voice in speech conversation system.
The present invention has been worked out in view of the drawbacks in the prior art set forth above. Therefore, it is an object of the present invention to provide a natural language conversation system which can make interaction between the user and the system smooth by continuing conversation with presenting guidance or with making the system to carry out speech for the user when user cannot response to presentation of the system to cause non-response, and can reduce load required for speech of user.
According to the first aspect of the present invention, a natural language conversation system comprises:
conversation control means for outputting data in a conversation scenario; and
alternative conversation means for alternatively inputting a preliminarily prepared natural language data to the conversation control means on behalf of a user when the user fails to input within a predetermined period.
According to the second aspect of the present invention, a storage medium storing a natural language conversation program operating a computer as conversation control means for outputting data in a conversation scenario, and alternative conversation means for alternatively inputting a preliminarily prepared natural language data to the conversation control means on behalf of a user when the user fails to input within a predetermined period.
In the preferred construction, the conversation control means may include holding means for holding a current state data indicative where a current state is in the conversation scenario, and the alternative conversation means may include an alternative input list containing a plurality of preliminarily prepared natural language data corresponding to the conversation scenario and means for selecting one of the natural language data depending up the current state data held in the holding means.
In short, the present invention implements presentation of a guide or performs alternative conversation in the system on behalf of the user for reducing load on the user for conversation, when the user cannot react on the presentation made by the system.